<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>学生管理 - 学生管理系统</title>
<link rel="stylesheet" href="../css/public.css">
<script>
function setActive() {
    var buttons = document.getElementsByTagName('button');
    for (var i = 0; i < buttons.length; i++) {
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            this.classList.add('active');
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</head>
<body onload="setActive()">
<header>
    <h1>学生管理系统</h1>
    <nav>
        <a href="../index.html"><button>首页</button></a>
        <button class="active">学生管理</button>
        <a href="clas.html"><button>班级管理</button></a>
    </nav>
</header>
<main>
    <h2>学生管理</h2>
    <p>这里是学生管理的内容。</p>
</main>
</body>
</html>